The present invention relates to a shock absorbing device for arresting the movement of a moving body and more specifically to shock absorbing device which uses a damper having a cylinder that slidingly receives a piston having an orifice and which is filled with a viscous fluid.
It is known that, in order to prevent the generation of impact noise which tends to be produced when a structure such as a cabinet door, or the like, is closed rapidly, a damper, which reduces the speed of the speed at which the door closes, can be disposed on a door stop of the cabinet.
As a damper for generating such damping force, there is known one that has a cylinder enclosing a viscous fluid, a piston which divides the interior of the cylinder into two axially separated sections and which has an orifice communicating the two sections, and a piston rod connected to the piston. This damper is arranged to generate a damping force (attenuating force) using the resistance produced by the viscous fluid passing through the orifice when the piston moves in the axial direction inside the cylinder together with the piston rod, which is known in Patent Document.
Japanese Patent No. 3465978
The above damper arrangement utilizes the property that the fluid resistance of the viscous fluid is increased progressively as the speed of movement of the piston becomes higher, and when used, for example as a door buffer device, it can be configured such that the resistance is low for gentle door closing operation and high for rapid door closing operation.
However, setting of the damping force is accomplished exclusively by the sizing of the aperture of the orifice provided in the piston, and there is a shortcoming that when the operating force at low speed is set appropriately, the damping force at high speed becomes rather insufficient, and conversely, when the damping force at high speed is set appropriately, the operability at low speed is impeded. Accordingly, it has been difficult to set the dynamic range of the damping force over a wide operating range.
The present invention has been made to obviate the above problems, and an object of the invention is to provide a damper which can set a dynamic range over a wide operating range.
Further objects and advantages of the invention will be apparent from the following description of the invention.